The present invention is novel cross-linked organofunctional polysiloxane and organofunctional cyclosiloxane compositions and a process for their preparation. The process for preparation of these siloxane compositions comprises contacting a mixture comprising a poly(organohydrogen)siloxane or a cyclo(organohydrogen)siloxane, a alpha,omega-triene, and a triorganosilyl source with a platinum catalyst, at a temperature within a range of 50.degree. C. to 200.degree. C. The products of this process are cross-linked organofunctional polysiloxanes and cross-linked organofunctional cyclosiloxanes. The triorganosilyl source added to the process provides for control of the amount of cross-linking of the organofunctional polysiloxanes and cyclosiloxanes independent of the level of organofunctionality.
The reaction of olefins with SiH-containing compounds is well known. For example, Wagner et al., U.S. Pat. No. 2,851,473, issued Sep. 9, 1958, describe the use of platinum deposited on the gamma allotrope of alumina to catalyze the reaction between molecules containing C.dbd.C bonds and SiH containing monomers.
British Patent No. 1,104,206, published Feb. 21, 1968, describes a process where a silicon compound containing at least one silicon-bonded hydrogen atom per molecule and not more than two hydrogen atoms attached to any one silicon atom is reacted with a compound containing aliphatically unsaturated carbon atoms in the presence of a platinum complex. Specific examples of compounds containing aliphatically unsaturated carbon atoms include compounds containing one and two unsaturated bonds.
German Patent Application No. P-2,166,867.7, published Apr. 22, 1976, describes a process where the reaction of trichlorosilane or methyldichlorosilane with a triene is catalyzed with platinum compounds to form bis-silyl olefins. The bis-silyl olefins are further reacted with polymeric unsaturated hydrocarbon chains in the presence of a Lewis acid and a metathesis catalyst to form polymeric hydrocarbons with reactive silyl terminal groups.
Brennan, U.S. Pat. No. 3,440,263, issued Apr. 22, 1969, describes a process in which olefinic compounds containing at least one ethylenic bond are reacted with siloxane polymers containing SiH bonds to form alkylated siloxanes. Platinum or platinum compounds supported on charcoal were reported as a suitable catalyst for the process.
Getson, U.S. Pat. No. 4,166,078, issued Aug. 28, 1979, describes a process where a modified polyorganosiloxane composition containing in situ generated particulate matter is prepared by reacting an poly(organohydrogen)siloxane with monomers containing aliphatic unsaturation in the presence of free radical initiators. Getson further describes a process where the modified polyorganosiloxane composition is reacted with a compound having at least two vinyl groups per molecule as a cross-linking agent and a catalyst which promotes the addition of SiH groups present in the modified polyorganosiloxane composition to vinyl groups of the cross-linking agent. Platinum is described as a suitable catalyst for the cross-linking process.
The object of the present invention is to provide a process for the production of cross-linked organofunctional siloxane compositions. The substitution of alpha,omega-trienes (.alpha.,.OMEGA.-trienes) for hydrogen on the silicon atoms of the siloxane is used to cross-link the siloxanes. The internal unsaturated bond of the .alpha.,.OMEGA.-triene is not effected by the platinum catalyst and thus remains intact imparting an organofunctionality to the cross-linked siloxane compositions. The amount of cross-linking of the siloxane compositions by the .alpha.,.OMEGA.-trienes is controlled by the addition of a triorganosilyl source, which can add across a terminal unsaturated bond of the .alpha.,.OMEGA.-triene. This allows for the level of cross-linking of the siloxane polymers to be varied while maintaining a constant level of organofunctionality and compatibility with organic compositions.